The present invention relates to a failure diagnosing method and apparatus for a controller mounted on a vehicle and, more particularly, to a method and apparatus adapted to prevent failure history data from being stored twice if a failure, which existed when a power source was cut OFF, has not yet been corrected.
A controller mounted on a vehicle or the like (hereinafter referred to as an xe2x80x9con-vehicle controllerxe2x80x9d) has been able to provide a higher function owing to the progress in the technologies in the semiconductor field, microcomputer field, and the like. On the other hand, the higher function has lead to a prolonged time for identifying the cause of a failure. An extended interruption of operation of the on-vehicle controller due to a failure means lower operating efficiency. Hence, there has been a strong demand from many users for achieving a shorter time for identifying the causes of failures. For this reason, more on-vehicle controllers employing microcomputers or the like are having built-in failure diagnosing functions.
According to a conventional failure diagnosing method, an on-vehicle controller is monitored at all times for a failure. If a failure occurs, then the cause or location of the failure is determined primarily by the failure detection signals received from mounted units, sensors, etc.; the failure detection signals issued from failure-detecting circuits; and the failure signals detected by the on-vehicle controller using software, and an operator is notified of the result by means of a display unit or the like. The operator takes a corrective action for the failure, then turns the power source of the vehicle back ON to check whether the failure has been corrected.
Further, in order to prevent a failure from taking place, some on-vehicle controllers record the history of the operating conditions (such as temperatures, pressures, and rotational speeds), the load conditions of the mounted units when they are operated, and the history of the causes and locations of failures that have happened in the past; and further use such history data to determine the tendency of failures, to carry out failure diagnosis. Stored in a history data storing area of the on-vehicle controller at predetermined timings are such history data as the oil temperature, speed, oil pressure, lubricant level, etc., of an engine; the oil temperature and lubricant level of a transmission; clutch operating time; ambient temperature; and atmospheric pressure. At the same time, the time at which the data was stored is also recorded. The data indicating the cause or location of a failure, when the failure happened, is stored together with the time at which the failure took place. Based on the history data, the tendency of the load state of each unit of the vehicle is determined to predict the service life thereof, or the frequency or tendency of the occurrence of failures is determined. Notifying the operator of those determined results enables the operator to carefully check a certain unit or replace a part, the service life of which is expected to expire soon, during periodic inspection, thus permitting preventive maintenance.
The on-vehicle controller carries out failure diagnosis whenever the power source is turned ON to make sure that the vehicle is in normal condition before allowing the functions to be put in operation. When the power source of the on-vehicle controller is turned OFF with a failure left uncorrected, the power source is frequently turned back ON before the cause of the failure has been removed. This causes the on-vehicle controller to decide that the failure from the same cause has occurred again when it carries out the diagnosis immediately after the power source thereof is turned back ON or after it is put in operation; hence, the time of the occurrence of that failure and the cause of the failure, etc. are stored again. Thus, the data on the same failure is stored twice since the power source was cut OFF with the failure left uncorrected. This poses a problem in that the on-vehicle controller fails to store necessary failure history data, preventing proper preventive maintenance from being implemented.
The present invention has been made with efforts focused on solving the problem described above, and it is an object of the invention to provide an on-vehicle controller failure diagnosing method and apparatus that make it possible, even if the power source of the on-vehicle controller is cut OFF with the presence of a failure and the power source is turned back ON with the failure uncorrected, to store proper history data without doubly recording the failure history data on the same failure.
According to a first aspect of the present invention, there is provided an on-vehicle controller failure diagnosing method for storing, if a vehicle failure happens, the time at which the failure happened and the details of the failure as failure history data; wherein the details of a failure, which occurred when the power source of the on-vehicle controller was cut OFF, are compared with the details of a failure detected by a failure diagnosis after the power source was turned back ON, and it is determined that the failure detected by the failure diagnosis after the power source was turned ON is a new failure only if the comparison result indicates that the details of the two failures are different, and the details of the detected failure are stored as failure history data.
Thus, if the details of the failure that occurred when the power source of the on-vehicle controller was cut OFF coincide with the details of the failure detected during the failure diagnosis carried out after the power source was turned back ON, then the on-vehicle controller determines that the corrective action for the failure that took place when the power source was cut OFF has not been completed or implemented; or it decides that a new failure has occurred only if the details of the foregoing two failures are different, and the details of the new failure are stored as failure history data. As a result, correct failure history data can be stored and hence accurate prediction of the tendency of failures or service lives can be accomplished, permitting highly accurate preventive maintenance.
According to a second aspect of the present invention, there is provided an on-vehicle controller failure diagnosing method for storing, if a vehicle failure happens, the time at which the failure happened, and the details of the failure are stored as failure history data, wherein it is determined, during a failure diagnosis carried out after a power source of the non-vehicle controller is turned back ON, whether the cause of a failure which existed when the power source was cut OFF has been eliminated; if the cause is found to be eliminated, it is determined that the failure which existed when the power source was cut OFF has been completely eliminated and the cause of the failure is stored as failure history data.
Thus, during failure diagnosis after the power source of the on-vehicle controller is turned ON, it is checked whether the cause of a failure, which existed when the power source was cut OFF, has been eliminated, and, if the cause is found to be eliminated, it is determined that the repair for the failure which existed when the power source was cut OFF has been completed, and the result is stored as failure history data. Hence, correct failure history data is stored and the tendency of failures and service lives can accordingly be predicted properly, permitting highly accurate preventive maintenance.
According to a third aspect of the present invention, there is provided an on-vehicle controller failure diagnosing apparatus equipped with failure detection means for detecting a failure of a vehicle and a means for storing failure history data for storing the details of the detected failure as failure history data, the on-vehicle controller failure diagnosing apparatus further including means for judging whether or not to store failure history data, which compares the details of a failure, detected by a failure diagnosis by the failure detection means, after a power source of the on-vehicle controller was turned back ON, with the details of a failure which have been stored in the means for storing failure history data and which existed when the power source was cut OFF, determines that the repair for the failure has not been completed if the details of the two failures coincide, and stores the details of the foregoing detected failure in the means for storing failure history data only if the details of the two failures are different.
Thus, the details of a failure, which existed when the power source of the on-vehicle controller was cut OFF, are stored in the means for storing failure history data; and the means for judging whether or not to store failure history data determines whether the details of a failure detected by a failure diagnosis, after a power source is turned ON, coincide with the details of the failure which have been stored in the means for storing failure history data and which existed when the power source was cut OFF. If the details of the two failures coincide, then the means for judging whether or not to store failure history data decides whether the repair for the failure which existed when the power source was turned OFF has not been completed, whereas if details of the two failures do not coincide, it decides that a new failure has occurred and stores the details of the failure as failure history data. As a result, correct failure history data can be stored and the tendency of failures and service lives can accordingly be predicted properly, permitting highly accurate preventive maintenance.